Preparation of Porous Mullite Ceramics Using Al as Foaming Agent

Abstract

Effects of Al in different added condition on pores shape and mullite configuration were investigated. Three sorts of hole were got by using Al as foaming agent in mullite composites. It was concluded that isolated holes could be formed by Al changing to Al2Ol3 with acidity condition in green state, open holes could be formed by Al changing to Al2O3 directly in sintering process, and mixed hole of isolated and open ones could be formed by Al changing to Al(OH)3 with alkalescence condition in green state followed changing to Al2O3 in sintering process. These holes could supply a position for growth of mullite as well.

Mullite (3Al2O3·2SiO2) ceramics obtained by reaction sintering of rice husk ash and alumina, phase evolution, sintering and microstructure

“…Porous mullite ceramic meet insulating material functions at high temperatures, also as materials for membrane filters of gases and liquids at elevated temperatures, as catalyst supports insulating or as insulating material. Porous mullite materials can be elaborated by different routes and different alumina and silica sources [26][27][28][29][30][31][32][33][34][35]. Moreover other by-products have been proposed as starting powders for mullite based materials [36][37][38][39][40][41].…”